rossiter’s exhauster. 763 
ounce of wax to the formula, and made it in the manner last described, which 
gave an ointment satisfactory in all respects. 
My conclusions from these experiments are either that the quantity of resin 
and wax be increased or the turpentine decreased, and that the resin, wax, and 
lard should be first melted, then removed from the heat, adding lastly the tujv 
pentine, thus preventing much waste. 
The Chairman then read the following letter from Mr. Rossiter, of Hastings, 
relative to an improved macerator or exhauster, which he had sent for exhibi¬ 
tion :— 
ROSSITER’S EXHAUSTER: AN IMPROVED APPARiUTUS EOR 
THE PREPARATION OF TINCTURES. 
The two systems now in use for the preparation of tinctures are each liable 
to certain objections, which are pretty generally acknowledged. 
In the process of maceration, the ingredients being allowed to settle at the 
bottom of the vessel, constant attention is required to disturb the spirit as it 
becomes saturated, or anything but a satisfactory result is obtained. 
On the other hand, many are deterred from adopting percolation from the 
costliness of the apparatus and the liability to breakage, besides the additional 
trouble entailed in first having to macerate the ingredients for a time before 
transferring to a percolator. 
Most pharmacists are agreed that the least troublesome, and perhaps the 
most efficient plan of any, is that of suspending the ingredient in the spirit, 
exhaustion being effected in a shorter time than in the ordinary way of mace¬ 
ration, and the shaking of the vessel unnecessary ; whilst the risk encountered 
in percolation, of the spirit forming a channel through any part of the ingre¬ 
dients not evenly packed, and so leaving portions untouched by its action, is 
avoided. 
In this process, as the spirit acts upon the solid matter and becomes more 
dense, it sinks to the bottom of the vessel and the fresher spirit rising to take 
its place, a descending and ascending current is established, which continues 
until the whole of the soluble properties are extracted. 
The apparatus which I have the honour of introducing to you, through the 
kindness of Mr. Haselden, is the result of my experimental endeavours to avail 
myself of this well-known law, brought to the most practically useful form I 
can devise. 
It provides a means of suspending the ingredients by a cage, made of pure 
tin, attached to a screw, which admits of its being raised or lowered to the exact 
level of the spirit, thus rendering it applicable for any small quantity of tinc¬ 
ture which it may be required to make. 
The outer vessel is of glass, fitted with a grooved wooden cover, which groove, 
to prevent evaporation of the spirit, is lined with india-rubber. An india- 
rubber ring also encircles the screw. 
The cage is easily shifted when the operation is completed, and is particularly 
convenient for transferring the contents to the press cylinder. 
The apparatus has also the advantage of being inexpensive and easily cleaned. 
The Chairman added, there seemed one little advantage which the inventor 
himself had not mentioned, viz. that when the tincture was completed, the 
ingredients could, by means of the screw, be drawn entirely out of the fluid, 
and allowed to drain before they were removed for pressing, so that there would 
be no loss. It seemed a very good idea for macerating tinctures or cold iu- 
fusions, though he could not admit that it would supersede percolation. 
3 i> 2 
